The present invention relates to a conveying unit for containers in filling machines.
The invention finds application to advantage in machines for filling containers both with liquid substances and with powder substances.
Such conveying units consist substantially of a main carousel rotatable about a vertical axis and supporting a supply tank containing the substances; the carousel receives a succession of containers each presenting a body and filler mouth, which are taken up at a first transfer station from a first rotary infeed conveyor.
The supply tank is equipped at the bottom with a plurality of filler valves, each of which can be associated with the mouth of a respective container in such a manner that when the carousel is set in motion, the tank rotates about the vertical axis and its contents are dispensed by way of the filler valves into the containers, whereupon the filled containers are directed by way of a second transfer station onto a second outfeed conveyor.
During the filling operation, more particularly, the containers revolve as one with the valves about the axis of rotation of the tank and are maintained in the correct filling position, that is to say, the filler mouth substantially in coaxial alignment with the relative valve, by a plurality of support and restraint assemblies. Each of these assemblies is equipped with two grippers, lower and upper, of which the relative jaws are positioned respectively to restrain the body and the neck of the individual container. More exactly, each gripper comprises a bracket element connected to a given point on the periphery of the main carousel, also a pair of jaws occupying a common plane and connected thus to the bracket element by way of relative pivots. The two jaws are interconnected by a spring of which the opposite ends are anchored to respective fixed pins rigidly associated with the jaws. The spring serves to maintain the two jaws in the gripping position, in which they combine to afford a seat proportioned to accommodate and restrain a part of the container body or the container neck, respectively. The edge profiles presented by the free ends of the jaws and by the contours of the seat are shaped according to the type and geometry of the container that is to be gripped: an expedient that serves, initially, to facilitate the take-up of the empty container into the seat during its transfer from the first infeed conveyor to the support and restraint assembly, and thereafter, to facilitate the release of the filled container during the course of its transfer from the support and restraint assembly to the second outfeed conveyor. Both the take-up movement and the release movement of the container are generated in a substantially radial direction, relative to the main carousel, overcoming the elastic force of the aforementioned spring, of which the tension will be appropriately calculated on a case by case basis.
Accordingly, it will be evident that the two jaws must remain permanently free to rotate about their respective pivots and that the spring likewise must maintain a correct tension over time, so that the take-up and release movements will always employ the same degree of force, otherwise the smooth operation of the machine could be jeopardized.
It is common practice with carousel type filling machines to obtain the long-term dependability in question by using pivots fashioned from special metallic materials and given a surface treatment such as will ensure durability from the structural standpoint, superior resistance to wear, and low friction, and likewise using a coil spring made of special material to ensure that its tension remains constant over time.
It has been found in practice, nonetheless, that the metal pivots of the gripper jaws tend to stray from their correct structural position and assume positions unable to guarantee smooth operation of the gripper over time; moreover, given the nature of the products being dispensed and the fact that these inevitably will come into contact with the metal components mentioned above, both the pivots and the coil springs of the grippers are attacked by the substances in question with the result that their operation is adversely affected. This means frequent servicing and/or frequent replacement of the affected parts, and correspondingly high costs.
The object of the present invention is to provide a unit for conveying containers, such as will be unaffected by the above drawbacks.
The stated object is realized according to the invention in a conveying unit for containers in filling machines, machines wherein the containers are held firm by a plurality of grippers each comprising a bracket element, a pair of jaws connected to the relative bracket element by way of corresponding pivots, and to advantage, at least one segment of elastic material connected separably by one end to at least one of the two gripper jaws through the agency of respective anchor means, said anchor means comprising: at least two knuckles fashioned integrally with the segment of elastic material, one at each end, at least two sockets afforded one by each gripper jaw serving to accommodate a respective knuckle end.